dog cant put on weight

I got a good lookin cur from a man who's yard he wanderd up in. Real leggy old timey looking young dog mabie a year or so old. Same way bag of bones you could count ribs and bumps on his back. Brought him home and its been 3 weeks or so now he looks good not fat but dang sure healthy. I wormed him real good 1st and most importantly and I fed him raw hamburger meat about a pound ever mornin and feed with about a half loaf of bread of an evening for 2 weeks along with liquid b12 on his feed. Slim as I call him has put on a lot of weight in the past few weeks using this method.